2015 IMPACT25 Athlete: Serena Williams

From line sketches to pencils and final color, Marvel captured the essences of our IMPACT25 nominees and turned them into super versions of themselves. Behind Marvel's IMPACT25 heroes »

"It wasn't a loss for me, it was a win and a learning experience." -- Serena Williams, after being upset by Roberta Vinci at the US Open

Is there anyone who can touch Serena Williams' dominance? After completing her second aptly titled Serena Slam (consecutive wins in the 2014 US Open, 2015 Australian Open, 2015 French Open and 2015 Wimbledon), the tennis icon set her sights on a calendar Grand Slam: winning all four majors in one calendar year.

Even when she was down -- she had the flu on the way to her third French Open title -- her spirit and ground strokes seemed unstoppable, her serve almost unanswerable.

She lost to Roberta Vinci in three sets in the semifinals of the US Open, surprising everybody.

Still, Serena finished her amazing year ranked No. 1 -- the third consecutive time she's landed at the top of the world -- and there's no doubt that Williams, at age 34, will keep on slammin'.